1. Field of the Invention
The present invention relates to an exterior structure provided on an electronic keyboard instrument.
2. Description of the Related Art
Conventionally, there is a known electronic keyboard instrument provided at its back surface with a speaker, and it is also known to mount the speaker on a periphery of a speaker-mounting hole formed in a back panel of the electronic keyboard instrument. A width of the electronic keyboard instrument is about 130 cm, the back panel is made of wood, synthetic resin, aluminum extrusion-molded material or the like, and design such as characters or drawings is made on a surface of the back panel. A porous speaker cover such as a punching metal is provided in front of a wall surface of the back panel for protecting the speaker.
The speaker cover is generally mounted on the back panel through a mounting hardware, but when the mounting hardware is used, there is inconvenience that the number of parts is increased and the number of assembling steps is also increased. However, when the speaker cover is mounted using screw without using the mounting hardware, there is inconvenience that the screw is exposed outside to mar the outward appearance. Further, since the electronic keyboard instrument is formed relatively small, precise positioning is required correspondingly so that the mounted speaker does not interfere with movable portions such as keyboards to detract from the acoustic characteristics, and it is desired to meet the requirements easily. Further, it is preferable to use a thin member as the back panel in order to lighten the electronic keyboard instrument, but a thin back panel is prone to cause vibration, the vibration affects vibration of a diaphragm of the speaker, and the acoustic characteristics of the speaker is detracted. Further, a display such as characters or drawings printed on the back panel, contamination or flaw is prone to adhere there to, and in order to prevent such contamination or flaw from the adhesion, a thin transparent film is stuck on the display until sales. However, the sticking operation is troublesome, and the display is relatively monotone and does not attract attention of the customer. Further, when the electronic keyboard instrument is formed compact, a clearance (indicated with symbol a in FIG. 2) between the keyboard mounted to a keybed of the instrument and the electronic part mounted on the back panel becomes narrow, and it is necessary to assemble with high precision. But in the conventional mounting method of the back panel, the back panel is superposed on the keybed and is screwed. Therefore, there is a problem that since the positioning precision is not sufficient, the keyboard and the electronic part will come in contact with each other to generate noise, or the keyboard is likely to be damaged.
It is an object of the present invention to provide an exterior structure of an electronic keyboard instrument in which acoustic characteristics are not detracted, outward appearance is excellent, the exterior structure can easily be produced and assembling precision is high.
To achieve the above object, the present invention provides an exterior structure for an electronic keyboard instrument comprising an extrusion-molded back panel provided on a back surface of an electronic keyboard instrument such as to extend in a direction in which keyboards are arranged, a speaker-mounting hole formed in a substantially upright or inclined wall surface of the back panel, a speaker mounted to the speaker-mounting hole, and a porous speaker cover is mounted in front of the wall surface, wherein a recess groove is formed at an upper portion of the back panel such as to extend in the direction in which the keyboards are arranged, an upper edge of the speaker cover is bent inward to form a locking edge, the locking edge is fitted into the recess groove, and a lower edge of the speaker cover is fixed to a lower portion of the back panel by a screw. Further, a positioning stopper which abuts against a back surface of a keybed of the electronic keyboard instrument and a fixing piece which abuts against a lower surface of the keybed are provided on a lower portion of the back pannel, thereby further enhancing the assembling precision. It is preferable that at least one of upper and lower portions of the back panel is formed with a reinforcing edge for the speaker cover, the reinforcing edge projecting forwardly from the wall surface.
In the present invention, when a thick plate having rigidness made of wood, synthetic resin or the like is provided around periphery of the speaker-mounting hole, excellent acoustic characteristics can be obtained even if the back panel is thin. According to the present invention, it is preferred that an exterior structure for an electronic keyboard instrument comprises an outer surface of the back panel provided with a display of character or drawing, wherein the speaker cover is formed into a size capable of covering substantially the entire surface of the wall surface, and each size or shape of holes of the porous speaker cover is differentiated at a front portion of the speaker and at a front portion of the display, and if desired, each angle of the holes of said porous speaker cover is differentiated at a front portion of said speaker and at a front portion of said display. This feature causes the outward appearance of the electronic keyboard instrument to excellence full of variation.